The invention relates to a method of forming a bundle of individual sheets according to the preamble of claim 1.
It is normally the case that, for the bundle-forming operation, banknotes are discharged from the separating mechanism to a transporting device at uniform spacings. With notes which are difficult to separate, the frictional drawing-off means of the separating mechanism is not always capable of delivering the notes in a uniformly separated manner.
It is then possible for all kinds of incorrect drawing-off operations to take place with banknotes which overlap in a flush manner, in imbricated form or even just in the edge region and with banknotes which follow one after the other at different spacings.
A series of sheets with irregular spacings or banknotes which overlap one another at a number of locations result in problems in terms of the sheets or banknotes being set down by the stacking wheel. The conventional stacking wheel has a multiplicity of closely adjacent paddles which form circle-arc-shaped slots with tangentially directed inlet openings, into which in each case one banknote is pushed. The action of pushing the banknotes into the continuously circulating stacking wheel generally does not pose any problems since the circumferential speed of the stacking wheel is very much slower than the transporting speed of the banknotes supplied. Since the paddles of the stacking wheel, furthermore, are very thin at their ends, there is no risk, in practice, of the banknotes striking against a paddle tip and thus being deflected from the path in their entirety.
With the correctly selected arrangement of the sheet conveyor and stacking wheel and with the correct relative speed, individually arriving notes are thus generally processed in a very reliable manner. If, however, the banknotes overlap or the spacing between them is too small, this may result in the banknotes no longer passing into the stacking-wheel gap and overshooting the stacking wheel into the set-down space. (It is possible here, in some circumstances, for the banknotes not to be gripped by the advancing conveyor and to remain in the transporting module.
With the correct arrangement, even overlapping banknotes may, if appropriate, still pass into the stacking wheel and be set down on the bundle. The arrangement here must be such that the following sheet or the following banknote is pushed beneath the banknote which is already located in the stacking wheel. If, on the other hand, the imbrication is the other way round, then the following sheet lifts up from the sheet running into the stacking wheel and overshoots the stacking wheel. The type of imbrication depends on the course of the transporting path between the separating apparatus and the stacking-wheel arrangement.
If the spacings between the sheets or banknotes are too short, this may result in a collision between the trailing edge of the banknote which has already run into the stacking wheel and the quickly following banknote, which is thus likewise deflected such that it shoots past the stacking wheel.
The object of the invention is to specify a method of the type mentioned in the introduction by means of which bundles of individual sheets can be formed reliably even when these individual sheets overlap wholly or partially or the spacing between two successive sheets is smaller than the minimum spacing which is necessary for normal operation.
This object is achieved according to the invention by the features specified in the characterizing part of claim 1.
In contrast to the known solution, in which the stacking wheel circulates continuously, the stacking wheel of the solution according to the invention is at a standstill when the sheet leaves the sheet conveyor and enters into the receiving gap of the stacking wheel. It is thus also possible for a plurality of overlapping sheets to be introduced into the same receiving gap of the stacking wheel, since the latter is only advanced when the trailing edge of the sheet leaving the sheet conveyor, or of the group of overlapping sheets, is detected. With a suitable design of the stacking wheel, it is thus readily possible for up to four sheets or banknotes to be gripped in a receiving gap of a stacking wheel. Since the stacking wheel is at a standstill as the sheets run in, the direction of imbrication is of no significance, i.e. even overlapping notes pass reliably into the stacking wheel irrespective of whether the following sheet is located above or beneath the preceding sheet.
As the above description demonstrates, sheets with the normal spacing and overlapping sheets are handled in the same way since, in both cases, the stacking wheel is only advanced when a trailing edge of an individual sheet or of a group of sheets is detected.
If, on the other hand, the spacings are too short, additional measures are necessary. The spacings can be gathered from the possible transporting speed and the number of sheets which are to be transported per unit of time. The minimum spacing which is to be maintained can be gathered, inter alia, from the times for advancing the stacking wheel. In order to ensure that successively spaced-apart sheets also pass into successive receiving gaps of the stacking wheel, the invention proposes that the spacing between a preceding sheet and a following sheet is detected within the sheet conveyor, that, when the spacing is smaller than a predetermined minimum spacing, the operation of the sheets being drawn off individually from the sheet-storage container is interrupted and the transporting speed is reduced until the preceding sheet has left the sheet conveyor, that the drive of the sheet conveyor is then stopped, that, once the preceding sheet has run into the stacking wheel, the stacking wheel is advanced, and that the drive of the sheet conveyor is switched on again.
As long as the actual sheet spacings are smaller than the predetermined minimum spacing, in this case, when the sheet-conveyor drive is switched on, the latter is controlled such that the sheet conveyor is first of all accelerated only to a fraction of the nominal speed.
In order for it to be possible to establish which kinds of drawing-off errors are occurring, it is expedient for the sheet thickness and the extent of the sheet in the transporting direction to be detected in the region of the sheet conveyor. This makes it possible to establish how many sheets are overlapping, in what way, and to what extent, they are overlapping, and whether individual sheets are possibly directed obliquely in relation to one another.
The invention also relates to an apparatus for forming a bundle of individual sheets, in particular banknotes, which are drawn off individually from a sheet-storage container, in particular for implementing the abovedescribed method, comprising a separating apparatus for drawing off the sheets from the sheet-storage container, a sheet conveyor, a drive for the sheet conveyor, a stacking-wheel arrangement, which is assigned to the outlet end of the sheet conveyor and has at least one stacking wheel and a stacking-wheel drive, a detector device, which is arranged in the region of the sheet conveyor and is intended for detecting an edge of a sheet running through the sheet conveyor, and a control device, which is connected to the separating apparatus, the drive of the sheet conveyor, the stacking-wheel drive and the detector device.
According to the invention, the stacking-wheel drive is designed here for an intermittent drive, and the control device is programmed such that the stacking wheel is stopped in a position in which the receiving gap of the stacking wheel is aligned with the outlet end of the sheet conveyor when a sheet leaves the sheet conveyor, and that, in dependence on an output signal from the detector device, said signal corresponding to the trailing edge of a sheet running into the receiving gap of the stacking wheel being detected, the stacking wheel is advanced by one receiving gap.
As has already been mentioned above, this arrangement ensures that individual sheets with the correct spacing or overlapping sheets pass reliably into the receiving gap of the stacking wheel since the latter is only advanced when it has been ensured that the respective sheet or the respective group of sheets has passed into the receiving gap and has left the sheet conveyor.
In order for it to be possible to determine the spacings between the successive sheets, a spacing-measuring device is arranged in the region of the sheet conveyor. It is also possible, in principle, for this purpose to use the abovementioned detector device, which supplies an edge signal, with the result that, from successive edge signals and the known transporting speed, the control device can determine the spacing between two successive sheets.
The detector device may comprise here a light barrier, which is arranged in the vicinity of the outlet end of the sheet conveyor.
A thickness-measuring device is also preferably provided in the region of the sheet conveyor, in order to detect the thickness of the sheets running through the sheet conveyor, by way of which it is possible to establish, in particular, whether sheets are overlapping. This is also important during the dispensing operation of banknotes in order to establish, for example, whether just one note is being dispensed or two notes overlapping in a flush manner are being dispensed. The thickness-measuring device here may have, for example, a lever gauge which is mounted such that it can be pivoted in relation to a rigid rest and of which the pivoting movement is converted into a corresponding signal.
In order, finally, to establish whether two or more sheets are partially overlapping, a length-measuring device is expediently provided in the region of the sheet conveyor, this device detecting the extent in the transporting direction of the sheets running through the sheet conveyor. In conjunction with the thickness measurement, this makes it possible to ascertain how many sheets are overlapping and in what way. The length-measuring device here may comprise at least one sensor for detecting a sheet edge, and may also comprise an encoder which is coupled to the drive of the sheet conveyor, the transporting speed being determined by said encoder. The length-measuring device preferably has at least two sensors which are spaced apart transversely to the transporting direction, with the result that oblique positioning of a sheet may also be detected. Since the thickness-measuring device also detects the presence and absence of sheets, it may likewise be used for measuring spacing and length.
During the intermittent operation of the stacking wheel, there is the problem of the stacking wheel, for the desired throughput of sheets, having to be accelerated to a very great extent during the advancement operation. There is a risk here of the sheet pushed into the receiving gap of the stacking wheel not being carried along by the stacking wheel. In particular if the note spacings are too narrow, it may be the case that the banknotes are already partially overlapping. Since the action of intersecting edges being pushed one above the other may result in the sheets or banknotes getting caught, it is necessary in such cases for the sheets to be drawn apart from one another. It is possible here for the following banknote to rest on the trailing edge of the banknote which is already located in the stacking wheel and to secure this latter banknote during the advancement operation, with the result that the banknote which is already located in the receiving gap of the stacking wheel is drawn out again.
In order to prevent such an effect, the invention proposes that the stacking wheel has a wheel hub with more or less tangentially directed paddles which are articulated resiliently on said wheel hub and of which in each case two adjacent paddles form a receiving gap for a sheet, the majority of the paddle mass being concentrated in the half of the paddle which is in the vicinity of the free paddle end.
This design of the stacking wheel results in the situation where in the initial accelerating phase of the stacking wheel, during advancement of the same, an inwardly directed radial force component acts on the paddles, with the result that the latter swing radially inward. The receiving gap thus closes and the sheet which is already located in the receiving gap is clamped in and carried along. As the circumferential speed of the stacking wheel increases, the centrifugal forces predominate again, these forces moving the paddles in the radially outward direction and opening the receiving gap, with the result that, on the stacking surface, the sheets can easily be stripped from the receiving gap.
The abovedescribed pivoting movement of the paddles in the radially inward direction may be enhanced by an additional mass being arranged in the vicinity of the free end of the paddle, said additional mass being of a higher density than the stacking-wheel material. The stacking wheel itself may be produced, for example, in one piece from plastic, the articulation between the paddles and the wheel hub and also the elastic restoring force being provided by a material bridge and the material itself. In contrast, the additional mass may consist of a piece of metal.
In order to improve the gripping of the banknote which is located in the receiving gap by the paddles, the paddles may bear a corrugated formation on their mutually facing surfaces.
In a preferred embodiment, the stacking wheel has four paddles which are offset in each case through 90 in relation to one another. In order to avoid the paddles spreading too far apart on account of the centrifugal force, the resilient deflection of the paddles in the radially outward direction may be limited in each case by a stop which is connected rigidly to the hub.
A stepping motor is preferably used for the drive of the stacking wheel.
It should be emphasized that the abovedescribed design of the stacking wheel is also suitable for uses other than in automatic teller machines or the like.